The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An airplane is moved by several turbojet engines each housed in a nacelle also housing a set of related actuating devices connected to its operation and performing various functions when the turbojet engine is running or stopped. These related actuating devices in particular comprise a mechanical thrust reversal system.
More specifically, a nacelle generally has a tubular structure comprising an air intake upstream of the turbojet engine, a middle section designed to surround a fan of the turbojet engine, a downstream section housing the thrust reverser means and designed to surround the combustion chamber of the turbojet engine, and generally ends with a jet nozzle whereof the outlet is situated downstream of the turbojet engine.
Modern nacelles are designed to house a dual flow turbojet engine capable of generating, via the rotating fan blades, a flow of warm air (also called primary flow) coming from the combustion chamber of the turbojet engine, and a flow of cool air (secondary flow) that circulates outside the turbojet engine through an annular channel, also called tunnel, formed between fairing of the turbojet engine and an inner wall of the nacelle. The two flows of air are discharged from the turbojet engine through the rear of the nacelle.
During landing of an airplane, the role of a thrust reverser is to improve the braking capacity of that airplane by reorienting at least part of the thrust created by the turbojet engine forward. In this phase, the reverser obstructs the annular channel for the flow of cool air and orients the latter toward the front of the nacelle, thereby creating a counter-thrust that is added to the braking of the wheels of the airplane.
The means implemented to perform this reorientation of the flow of cool air vary depending on the type of reverser. However, in all cases, the structure of the reverser comprises cowls that can be moved between a deployed (or reverse jet) position, in which they open a passage in the nacelle designed for the deflected flow, on the one hand, and a retracted (or “direct jet”) position, in which they close that passage.
In the case of a reverser with gratings, also known as a cascade reverser, the reorientation of the flow of air is done by cascades, the cowl being slidingly mounted along the axis of the nacelle so as to expose or cover those gratings. Complementary blocking doors, also called reverser flaps, activated by the sliding of the cowling, generally allow closing of the annular cool air flow channel downstream of the gratings so as to optimize the reorientation of that flow of air.
The sliding of the moving cowl between its “direct jet” and “reverse jet” positions is ensured by cylinders distributed on the periphery of the nacelle.
Traditionally, the cylinders are fastened upstream on a stationary part of the nacelle, such as the front support frame of the cascades, and downstream inside the moving cowl, using adapted fittings.
More specifically, the actuating rods of the cylinders pass through the rear support frame of the cascades to cooperate with the moving cowl.
This necessarily means that the rear frame of the cascades has a certain radial bulk.
However, in modern nacelles, where efforts are made to reduce aerodynamic losses due to wet surfaces, the lines are increasingly compact, and it is particularly important to be able to reduce the radial thickness of the rear frame.